The proposed longitudinal study is designed to examine reading development at critical points in its establishment (from ages 7.5-10.5) in nonimpaired (Nl) and reading disabled (RD) cohorts. Our previous cross sectional research has identified reading group differences in both functional neuroanatomical and behavioral trajectories; the proposed longitudinal study is aimed at gaining a better understanding of behavioral, neurobiological, and genetic etiological factors responsible for this observed divergence. We examine the hypothesis that the candidate etiological agent that might underlie variation in neurodevelopmental and behavioral trajectories is gamma-aminobutyric acid (GABA): research has shown that GABA plays a critical role in learning and memory. Accordingly, the proposed research will permit relating developmental changes in reading performance and functional neuroanatomy for reading (measured with fMRI) to GABA expression, measured with magnetic resonance spectroscopy (MRS) and genetic analyses, linking polymorphisms in the GABA family genes to GABA expression in the brain. Specifically, the research aims to: 1) Characterize concurrent relations among genetics, neurochemistry, functional neuroanatomy, and reading behavior at 2 important timepoints in reading development, 2) Investigate Nl and RD differences for each of these measures, 3) Examine subsequent developmental trajectories in Nl and RD cohorts, 4) Better characterize learning capacities and learning styles in these cohorts, 5) Develop dynamic brain/behavior phenotypes sensitive to genetic analyses, and 6) Contrast multi-level profiles and developmental trajectories in subgroups of RD.